Thermal insulation containing supplemental infrared radiation absorbing material

ABSTRACT

A thermal insulation product includes an infrared radiation absorbing and scattering material dispersed on fibers forming a porous structure. The infrared absorbing and scattering material can include borate compounds, carbonate compounds, and alumina compounds.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to thermal insulation. More specifically, thisinvention relates to thermal insulation containing infrared radiation(“IR”) absorbing and scattering material, which reduces radiative heattransfer through the thermal insulation.

2. Description of Related Art

Heat passes between two surfaces having different temperatures by threemechanisms: convection, conduction and radiation. These heat transfermechanisms are combined in a quantitative measure of heat transfer knownas “apparent thermal conductivity.”

Insertion of glass fiber thermal insulation in the gap between twosurfaces reduces convection as a heat transport mechanism because theinsulation slows or stops the circulation of air. Heat transfer byconduction through the glass fiber of the insulation is also minimal.However, many glass compositions used in glass fiber insulation productsare transparent in portions of the infrared spectrum. Thus, even whenthe gap between surfaces has been filled with glass fiber thermalinsulation, radiation remains as a significant heat transfer mechanism.Typically, radiation can account for 10 to 40% of the heat transferredbetween surfaces at room (e.g., 24° C.) temperature.

Fiber to fiber radiative heat transfer is due to absorption, emissionand scattering. The amount of radiative heat transfer between fibers dueto emission and absorption is dependent on the difference in fibertemperatures, with each fiber temperature taken to the fourth power.

To reduce radiative heat loss through thermal insulation, a number ofapproaches have been considered.

U.S. Pat. No. 2,134,340 discloses that multiple reflections of infraredradiation from a powder of an infrared transparent salt, such as calciumfluoride, added to glass fiber insulation can prevent the infraredradiation from penetrating any substantial distance into the insulation.

U.S. Pat. No. 5,633,077 discloses that an insulating material combiningcertain chiral polymers with fibers can block the passage of infraredradiation through the insulating material.

U.S. Pat. No. 5,932,449 discloses that glass fiber compositionsdisplaying decreased far infrared radiation transmission may be producedfrom soda-lime borosilicate glasses having a high boron oxide contentand a low concentration of alkaline earth metal oxides.

There remains a need for a cost effective thermal insulation productthat can reduce radiative heat loss.

SUMMARY OF THE INVENTION

A thermal insulation product is provided in which an IR absorbing andscattering material is dispersed on fibers arranged in a porousstructure. The IR absorbing and scattering material can be applied tothe fibers before or after the fibers are formed into the porousstructure. The IR absorbing and scattering material substantiallyreduces the radiative heat loss through the thermal insulation.Inclusion of the IR absorbing and scattering material improves theeffective wavelength range over which the porous structure absorbsinfrared radiation and improves its overall extinction efficiency. TheIR absorbing and scattering material is about as effective as glassfiber in reducing radiative heat loss through a porous fiber structure,but can be much less expensive than glass fiber. Hence, the IR absorbingand scattering material can provide a cost-effective means of improvingthermal insulation.

BRIEF DESCRIPTION OF THE DRAWINGS

The preferred embodiments of the invention will be described in detail,with reference to the following figures, wherein:

FIG. 1 shows the absorption spectra of silica, glass fiber, calciumcarbonate and borax;

FIG. 2 shows a method of applying IR absorbing and scattering materialto fibers;

FIG. 3 shows a method of adding IR absorbing and scattering material toan unbonded glass fiber mat;

FIG. 4 shows a method of applying IR absorbing and scattering materialto fibers including recycled fiberglass; and

FIG. 5 shows a method of applying IR absorbing and scattering materialto fibers.

FIG. 6 shows a method of forming pipe insulation by wrapping aninsulation mat around a mandrel.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The present invention reduces the radiant transmission of heat through afiber based thermal insulation product by dispersing an IR absorbing andscattering material onto the fibers. Because the IR absorbing andscattering material can be less expensive than the fiber, thesubstitution of the IR absorbing and scattering material for some of thefiber can lead to a significant cost reduction in thermal insulation.

A suitable IR absorbing and scattering material absorbs and scattersinfrared radiation with a wavelength in the 4 to 40 μm range.Preferably, the IR absorbing and scattering material absorbs 6-8 μm(1667-1250 cm⁻¹) infrared radiation. The IR absorbing and scatteringmaterial can include borate compounds, carbonate compounds, aluminacompounds, nitrate compounds and nitrite compounds. These compounds canbe alkali metal salts or alkaline earth metal salts. Borate compounds,carbonate compounds and alumina compounds are preferred. Suitableborates include lithium borate, sodium borate, potassium borate,magnesium borate, calcium borate, strontium borate and barium borate.Preferably, the borate is sodium borate (i.e., borax, Na₂B₄O₅(OH)₄·8H₂Oor Na₂B₄O₇·10H₂O) or colemanite (Ca₂B₆O₁₁·5H₂O). Suitable carbonatesinclude lithium carbonate, sodium carbonate, potassium carbonate,calcium carbonate (i.e., calcite, CaCO₃), dolomite (CaMg(CO₃)₂),magnesium carbonate (i.e., magnesite, MgCO₃), strontium carbonate andbarium carbonate. Preferably, the carbonate is calcium carbonate,dolomite, or magnesite. Suitable alumina compounds include hydratedalumina (AlO₂O₃O·3H₂O or Al(OH)₃) and alumina (Al₂O₃). ALCOA producesHYDRAL and B-303 particles of hydrated alumina.

The infrared absorbing and scattering material is useful in improvingthe thermal resistance of a porous thermal insulation product containingfibers. In particular, carbonate compounds and alumina compounds areuseful in improving the thermal resistance of porous thermal insulationcontaining fibers at temperatures of 300° C. or more or even 400° C. ormore.

FIG. 1 shows the absorption spectra of borax and calcium carbonate. Theabsorption characteristics of borax and calcium carbonate complementthose of glass fiber and silica, which have been used commercially inthermal insulation for over fifty years.

The amount of IR absorbing and scattering material in the thermalinsulation product can range from 1 to 40 wt %, preferably from 2 to 30wt %, more preferably from 4 to 20 wt %. If the amount of IR absorbingand scattering material is less than 1 wt %, then the reduction inradiative heat loss is negligible. If the amount of IR absorbingmaterial is in excess of 40 wt %, then the IR absorbing and scatteringmaterial forms an undesirable amount of dust in the thermal insulationproduct.

The fibers in the thermal insulation product can be organic orinorganic. Organic fibers include cellulose fibers; cellulosic polymerfibers, such as rayon; thermoplastic polymer fibers, such as polyester;animal fibers, such as wool; and vegetable fibers, such as cotton.Preferably, the fibers are inorganic. Inorganic fibers include rock wooland glass wool. Preferably, the inorganic fibers comprise a glass.

The fibers form a porous structure. The porous structure can be woven ornonwoven. Preferably, the porous structure is nonwoven. The nonwovenfibers can be in the form of a batt, mat or blanket. A preferred porousstructure is that found in FIBERGLASS.

Along with the fibers and IR absorbing and scattering material, thethermal insulation product can include a binder to capture and hold thefibers and IR absorbing material together. The binder can be athermosetting polymer, a thermoplastic polymer, or an inorganic bondingagent. Preferably, the thermosetting polymer is a phenolic resin, suchas a phenol-formaldehyde resin. The thermoplastic polymer will soften orflow upon heating to capture the fibers and IR absorbing and scatteringmaterial, and upon cooling and hardening will hold the fibers and IRabsorbing and scattering material together. In embodiments of thepresent invention, the IR absorbing and scattering material can itselfbond fibers together and thus render the addition of a binderunnecessary. When binder is used in the thermal insulation product, theamount of binder can be from 1 to 35 wt %, preferably from 3 to 30 wt %,more preferably from 4 to 25 wt %.

The thermal insulation product of the present invention can be formed bydispersing the IR absorbing and scattering material on to the surface offibers, and by forming the fibers into a porous structure. The dispersedIR absorbing and scattering material can be in the form of particles.The optimum particle size is around 4 μm. Preferably 99% of theparticles are less than 10 μm in size. The infrared absorbing andscattering material can be dispersed on the fibers before or at the sametime or after the fibers are formed into the porous structure. Methodsof forming fibers into porous structures are well known to the skilledartisan and will not be repeated here in detail.

FIG. 2 shows a method of depositing IR absorbing and scattering materialon glass fibers. Glass fibers 21 pass through a water overspray ring 23and a binder application ring 22. Tank 24 is connected via lines 25 and26 to rings 22 and 23, respectively. In tank 24 an IR absorbing andscattering material is dissolved or suspended in a liquid mixture. TheIR absorbing and scattering material is applied to the glass fibers 21by injecting the liquid mixture from tank 24 into the binder applicationring 22 and/or the water overspray ring 23. The liquid mixture caninclude water and various surfactants and suspension agents. If the IRabsorbing and scattering material is not completely dissolved in theliquid mixture, the liquid mixture must be agitated to keep the IRabsorbing and scattering material in suspension. The spray nozzles inrings 22 and 23 have nozzle orifices large enough to permit undissolvedIR absorbing and scattering materials to pass through the nozzleswithout clogging.

FIG. 3 shows an embodiment in which binder and IR absorbing andscattering material are dispersed from gravity feeder 30 on top of loosefibers 31 that have been distributed across the width of a conveyor 32to form a porous mat. The IR absorbing and scattering material isintroduced into the porous mat separately from or premixed with abinder. The binder can be a dry powder. The fibers with binder and IRabsorbing and scattering material dispersed on the fibers then passthrough a mat forming unit 33 where they are mixed and delivered intothe air lay forming hood 34. The binder and IR absorbing and scatteringmaterial may also be added at the mat forming unit 33. The mix is thencollected through negative pressure on another conveyor (not shown) andtransported into a curing oven 15. When passed through curing oven 35,the binder melts, cures, and binds together the IR absorbing materialand fiber.

FIG. 4 shows an embodiment in which a recycling fan 41 is used to suckin and mix IR absorbing material (e.g., calcium carbonate powder) fromfan intake 42 and recycled glass fiber from fan intake 43. The IRabsorbing and scattering material and recycled glass fibers are blownfrom fan 41 at exit 44 into a forming hood (not shown). There themixture is dispersed on glass fiber, together with a binder, ifnecessary. After passing through a curing oven (not shown) the IRabsorbing and scattering material materials and glass fibers are bondedtogether.

FIG. 5 shows an embodiment in which a metering feeder 51 feeds the dry,powder IR absorbing and scattering material into a blowing fan 52. TheIR absorbing and scattering material is blown by the fan into theforming hood 53 and dispersed on glass fiber with a binder, ifnecessary. Multiple feeders and blowing fans may be used.

FIG. 6 shows embodiments in which thermal pipe insulation is produced bywrapping an insulation mat 61 around a hot mandrel or pipe 62 to form asection of pipe insulation having one or more layers of the insulationmat 61. Preferably the section of pipe insulation is cylindrical.Infrared absorbing and scattering material 63, in liquid or powder form,can be deposited by, e.g., spraying, onto the insulation mat 61 from ainfrared absorbing and scattering material source 64 while theinsulation mat 61 is on the mat production line and before theinsulation mat 61 is wrapped around the mandrel 62. The infraredabsorbing and scattering material preferably includes at least onecarbonate or alumina compound.

EXAMPLES

The following non-limiting examples will further illustrate theinvention.

Example 1

FIBERGLASS samples are prepared in a laboratory with either borax{Na₂B₄O₇·10H₂O} or calcium carbonate dispersed throughout as IRabsorbing and scattering materials. The samples are 30.5 cm wide×30.5 cmlong×2.5 cm thick. The IR absorbing materials are weighed and mixed in asolution of 30% isopropanol and 70% water. The borax is dissolved in thewater using a mixer and a hot plate to form a borax solution. Thecalcium carbonate is mixed in the alcohol/water by hand to form acalcium carbonate suspension. The liquid mixtures containing the IRabsorbing and scattering material are loaded onto the samples either bysoaking or by spraying. The soaking is performed by pouring 240 ml ofone of the liquid mixtures onto each sample and soaking the sample. Thespraying is performed by using a spray bottle to spray 120 ml of one ofthe liquid mixtures onto each sample. The apparent thermal conductivityof each of the samples is measured before and after the IR absorbingmaterial is added. The apparent thermal conductivities are shown inTable 1. TABLE 1 Reduction in apparent IRM* Apparent thermal added tothermal conductivity fiberglass conductivity** through the IRM* or vsvirgin before addition addition of Fiberglass ground sample of IRM* orIRM* or density glass Application weight ground glass ground glassSample (kg/m³) powder Method (wt %) powder powder 1 8.71 CaCO₃ Soaking 5.5% 43.01 1.9% 2 10.5 CaCO₃ Soaking 13.3% 41.26 2.2% 3 7.02 CaCO₃Soaking 14.9% 47.72 3.0% 4 8.38 CaCO₃ Soaking 23.0% 44.23 4.9% 5 9.12CaCO₃ Soaking   48% 42.96 5.8% 6 10.6 Ground Soaking   24% 40.74 2.5%glass, same composition as the glass fiber 7 6.76 Borax Spraying  3.1%49.14 0.6% 8 7.27 Borax Soaking  8.6% 47.64 1.7%*IRM = infrared absorbing and scattering material**Thermal conductivity units = (mW/m · ° C.) tested by ASTM C518 testmethod at 24° C. mean temperature

Table 1 shows that the addition of borax or calcium carbonate toFIBERGLASS results in a reduction in the apparent thermal conductivityof the insulation. For the samples with calcium carbonate, thepercentage reduction in thermal conductivity is roughly proportional tothe percentage of calcium carbonate applied to the FIBERGLASS.

Comparative samples showing the reduction in apparent thermalconductivity produced by adding glass fiber to insulation are providedby standard R11, R13 and R15 FIBERGLASS insulation, as shown in Table 2.TABLE 2 Apparent Reduction in thermal thermal R-Value Added glassconductivity** conductivity at fiber relative to before the throughaddition 8.9 cm Density R11 addition of glass of glass fiber Thick(kg/m³) (wt %) fiber (%) R11 8.59 — 45.88 — R13 12.8  49.3 38.82 15.4R15 22.4 160.6 33.64 26.7**Thermal conductivity units = (mW/m · ° C.) tested by ASTM C518 testmethod at 24° C. mean temperature

Example 2

Two sets of FIBERGLASS samples of varying compositions in a fiberglassinsulation manufacturing process are prepared. The first set of samplesis maintained as a reference. To the second set of samples is added 12wt % calcium carbonate. The apparent thermal conductivity at 24° C. meantemperature of each sample as a function of density is determined byASTM test procedure C518 and shown in Table 4. TABLE 3 Apparent thermalFiberglass Apparent thermal conductivity** standard Densityconductivity** standard product with kg/m³ product 12 wt % CaCO₃ 8.0147.41 48.09 8.97 45.16 45.75 11.2 41.41 41.90 12.6 39.83 40.26 12.839.57 39.99 14.4 38.18 38.56**Thermal conductivity units = (mW/m · ° C.) tested by ASTM C518 testmethod at 24° C. mean temperature

Using the data in Table 3, the reduction in apparent thermalconductivity resulting from the addition of calcium carbonate iscompared with the reduction in apparent thermal conductivity resultingfrom an increase in glass density in the FIBERGLASS insulation. Theresults are shown in Table 4. TABLE 4 Reduction in Reduction inReduction in apparent apparent apparent Range thermal thermal thermalover which conductivity** conductivity** conductivity** glass densityfrom 12% from 12 wt % by CaCO₃ (kg/m³) increase in addition of comparedto increased 12% glass fiber density CaCO₃ glass fiber From 8.01 to 8.974.7% 3.5% 74% From 11.2 to 12.6 3.8% 2.8% 74% From 12.8 to 14.4 3.5%2.5% 71%**Thermal conductivity = (mW/m · ° C.) tested by ASTM C518 test methodat 24° C. mean temperature

Table 4 shows that the addition of 12 wt % calcium carbonate toFIBERGLASS is approximately 73% as effective as a 12% increase inFIBERGLASS density in reducing the apparent thermal conductivity ofFIBERGLASS thermal insulation. Thus, about 1.37 (=1/0.73) times as muchcalcium carbonate as glass fiber must be added to achieve the samereduction in apparent thermal conductivity.

However, the cost of calcium carbonate can be less than 50% of the costof glass fiber. Thus, the cost for reducing the thermal conductivity ofFIBERGLASS insulation with calcium carbonate can be 68%(=(100)(1.37)(0.50)) or less than that of the cost of the same thermalconductivity reduction with glass fiber. Thus, calcium carbonate is amore cost-effective additive to FIBERGLASS than glass fiber for reducingthe apparent thermal conductivity of the thermal insulation.

Example 3

A fiberglass insulation sample with 12 wt % calcium carbonate isprepared in a fiberglass manufacturing process. Table 5 shows thereduction in apparent thermal conductivity at various temperaturescompared to a fiberglass insulation sample with no calcium carbonate.TABLE 5 Reduction in Apparent thermal Reduction in apparent thermalconductivity** apparent thermal conductivity** by CaCO₃ test temperatureconductivity** compared to a 12 wt % (product density = from 12 wt %weight increase 24 kg/m³) addition of CaCO₃ with glass fiber  10° C.0.6% 24%  50° C. 4.6% 132% 400° C. 19.2% 233%**Thermal conductivity units = (mW/m · ° C.) tested by ASTM C518 testmethod.

Example 5

FIBERGLASS samples are prepared in a laboratory using hydrated aluminadispersed throughout as an IR absorbing and scattering material. Thehydrated alumina is dispersed throughout the samples by spraying. Thehydrated alumina is produced by ALCOA in the form of 1 μm particles(HYDRAL H710), 2 μm particles (HYDRAL H716), and 3.8 μm particles(B-303). The samples are 61 cm wide×61 cm long×2.5 cm thick. Theapparent thermal conductivity at room temperature of each of the samplesis measured before and after the hydrated alumina is added. The resultsare shown in Table 6. TABLE 6 Thermal Thermal Fiberglass densityFiberglass density conductivity** conductivity** Reduction in withoutIRM* with IRM* IRM* added before addition of after addition of thermalIRM* (kg/m³) (kg/m³) (wt %) IRM* IRM* conductivity** HYDRAL H716 9.199.57 4.22% 42.62 42.06 −1.32% (2 μm) HYDRAL H716 9.21 9.61 4.29% 42.4041.68 −1.70% (2 μm) HYDRAL H716 7.57 7.96 5.21% 45.31 44.48 −1.84% (2μm) HYDRAL H716 11.19 11.58 3.43% 39.66 39.28 −0.98% (2 μm) Average:4.29% Average: −1.46% HYDRAL H716 10.61 11.38 7.26% 41.24 40.40 −2.03%(2 μm) HYDRAL H716 11.18 11.96 7.02% 40.37 39.62 −1.86% (2 μm) HYDRALH716 9.08 9.87 8.61% 43.15 42.09 −2.47% (2 μm) HYDRAL H716 10.60 11.387.39% 40.65 39.72 −2.27% (2 μm) Average: 7.57% Average: −2.16% HYDRALH710 6.92 7.29 5.39% 46.17 45.37 −1.72% (1 μm) HYDRAL H710 7.95 8.385.37% 43.97 43.43 −1.25% (1 μm) HYDRAL H710 8.96 9.38 4.72% 42.13 41.68−1.06% (1 μm) HYDRAL H710 8.47 8.89 4.93% 43.47 42.82 −1.49% (1 μm)Average: 5.10% Average: −1.38% HYDRAL H710 8.97 9.77 8.82% 42.52 41.22−3.05% (1 μm) HYDRAL H710 6.96 7.75 11.39%  48.41 46.73 −3.48% (1 μm)HYDRAL H710 7.90 8.68 9.90% 44.84 43.74 −2.44% (1 μm) HYDRAL H710 10.5111.31 7.57% 42.35 41.28 −2.52% (1 μm) Average: 9.42% Average: −2.87%B-303 10.41 10.80 3.78% 42.06 41.50 −1.34% (3.8 μm) B-303 7.00 7.375.36% 47.45 46.60 −1.79% (3.8 μm) B-303 7.90 8.29 5.00% 45.57 44.71−1.90% (3.8 μm) B-303 9.05 9.43 4.17% 42.85 42.12 −1.72% (3.8 μm)Average: 4.58% Average: −1.69% B-303 8.89 9.63 8.40% 42.66 41.19 −3.45%(3.8 μm) B-303 9.35 10.14 8.38% 40.60 39.85 −1.85% (3.8 μm) B-303 10.1210.89 7.55% 41.08 40.24 −2.04% (3.8 μm) B-303 10.78 11.56 7.16% 40.6339.87 −1.88% (3.8 μm) Average: 7.87% Average: −2.30%*IRM = infrared absorbing and scattering material**Thermal conductivity units = (mW/m · ° C.) tested by ASTM C518 testmethod at 24° C. mean temperature

The results in Table 5 show that the addition of hydrated aluminaparticles to FIBERGLASS can reduce the room temperature thermalconductivity of the FIBERGLASS and thus improve the insulationproperties of FIBERGLASS.

The thermal conductivity of FIBERGLASS samples with and withoutdispersed hydrated alumina in the form of 1 μm particles (HYDRAL H710)is measured at 300° C. The results are shown in Table 7. The datarepresents averaged values from eight samples having identicaldimensions. One set of averaged values is from four of the samplescontaining dispersed hydrated alumina. The other set of averaged valuesis from four reference samples that do not include hydrated aluminaparticles. TABLE 7 Density Temperature Thermal (kg/m³) (° C.)Conductivity** Reference 11.8 300 206.9 Fiberglass with 11.7 300 202.69.4 wt % Hydral H710 (1 μm)**Thermal conductivity units = (mW/m · ° C.) tested by the ISO 8302(equivalent to ASTM C 177-85) test method at 300° C. mean temperature

Table 7 shows that show that the addition of hydrated alumina particlesto FIBERGLASS can reduce the 300° C. thermal conductivity of theFIBERGLASS by about 2.1% and thus improve the high temperatureinsulation properties of the FIBERGLASS.

The disclosure of the priority document, U.S. application Ser. No.09/858,471, filed May 17, 2001, is incorporated by reference herein inits entirety.

While the present invention has been described with respect to specificembodiments, it is not confined to the specific details set forth, butincludes various changes and modifications that may suggest themselvesto those skilled in the art, all falling within the scope of theinvention as defined by the following claims.

1. A thermal insulation product comprising fibers; and an infraredabsorbing and scattering material dispersed on the fibers, wherein theinfrared absorbing and scattering material comprises at least onecompound selected from the group consisting of carbonate compounds,borate compounds, and alumina compounds; and the product furthercomprises a porous structure.
 2. The product according to claim 1,wherein at least a portion of the infrared absorbing and scatteringmaterial is dispersed on fibers inside the thermal insulation product.3. The product according to claim 1, wherein the porous structure isnonwoven.
 4. The product according to claim 1, wherein the fibers areinorganic.
 5. The product according to claim 1, wherein the fiberscomprise a glass.
 6. The product according to claim 1, wherein theproduct comprises the infrared absorbing and scattering material in anamount of from 1 to 40% by weight.
 7. The product according to claim 1,wherein the infrared absorbing and scattering material comprises acarbonate compound selected from the group consisting of calciumcarbonate, dolomite and magnesite.
 8. The product according to claim 1,wherein the infrared absorbing and scattering material comprises aborate compound selected from the group consisting of borax andcolemanite.
 9. The product according to claim 1, wherein the infraredabsorbing and scattering material comprises hydrated alumina.
 10. Theproduct according to claim 1, further comprising a binder selected fromthe group consisting of thermosetting polymers, thermoplastic polymers,and inorganic compounds.
 11. The product according to claim 1, whereinthe infrared absorbing and scattering material absorbs infraredradiation having a wavelength in a range of 4 to 40 μm.
 12. The productaccording to claim 11, wherein the infrared absorbing and scatteringmaterial absorbs infrared radiation having a wavelength in a range of 6to 8 μm.
 13. Use of an infrared absorbing and scattering materialcomprising at least one compound selected from the group consisting ofcarbonate compounds, borate compounds, and alumina compounds to improvethe thermal resistance of a thermal insulation product comprisingfibers, the infrared absorbing and scattering material being dispersedon the fibers, wherein the product further comprises a porous structure.14. Use of an infrared absorbing and scattering material comprising atleast one compound selected from the group consisting of carbonatecompounds and alumina compounds to improve the thermal resistance at atemperature of 300° C. or more of a thermal insulation productcomprising fibers, the infrared absorbing and scattering material beingdispersed on the fibers, wherein the product further comprises a porousstructure.
 15. Use of an infrared absorbing and scattering materialcomprising at least one compound selected from the group consisting ofcarbonate compounds and alumina compounds to improve the thermalresistance at a temperature of 400° C. or more of a thermal insulationproduct comprising fibers, the infrared absorbing and scatteringmaterial being dispersed on the fibers, wherein the product furthercomprises a porous structure.
 16. A method of forming a thermalinsulation product, the method comprising dispersing on fibers aninfrared absorbing and scattering material comprising at least onecompound selected from the group consisting of carbonate compounds,borate compounds, and alumina compounds; and forming the fibers into aporous structure.
 17. The method according to claim 16, wherein theinfrared absorbing and scattering material comprises calcium carbonate.18. The method according to claim 16, wherein the dispersing comprisessoaking or spraying the fibers with a liquid mixture containing theinfrared absorbing and scattering material.
 19. The method according toclaim 18, wherein the infrared absorbing and scattering material issuspended in the liquid mixture.
 20. The method according to claim 16,wherein the infrared absorbing and scattering material is dispersed onthe fibers after the fibers are formed into the porous structure. 21.The method according to claim 16, wherein the dispersing comprisesmixing the infrared absorbing and scattering material and the fibers.22. The method according to claim 16, wherein the dispersing comprisesmixing the infrared absorbing and scattering material and the fibers;heating the infrared absorbing and scattering material; and binding thefibers together with the infrared absorbing and scattering material. 23.The method according to claim 16, wherein the mixing comprises suckingor blowing a dry powder of the infrared absorbing and scatteringmaterial into the porous structure.
 24. The method according to claim16, wherein the dispersing comprises mixing the infrared absorbing andscattering material, the fibers, and a binder.
 25. The method accordingto claim 16, wherein the dispersing comprises mixing the infraredabsorbing and scattering material and the fibers with a binder; heatingthe binder; and binding the fibers and the infrared absorbing andscattering material together with the binder.
 26. The method accordingto claim 25, wherein the mixing comprises sucking or blowing the binderand a dry powder of the infrared absorbing and scattering material intothe porous structure.
 27. The method according to claim 16, wherein theporous structure is nonwoven.
 28. The method according to claim 16,wherein the fibers are inorganic.
 29. The method according to claim 16,wherein the fibers comprise a glass.
 30. The method according to claim16, wherein the infrared absorbing and scattering material comprises acompound selected from the group consisting of carbonate compounds andalumina compounds.
 31. The method according to claim 16, furthercomprising forming the porous structure into a pipe section comprisingthe infrared absorbing and scattering material and the fibers.
 32. Themethod according to claim 31, wherein the infrared absorbing andscattering material is dispersed on the fibers before the porousstructure is formed into the pipe section.